fs: push i_mutex and filemap_write_and_wait down into ->fsync() handlers

Btrfs needs to be able to control how filemap_write_and_wait_range() is called
in fsync to make it less of a painful operation, so push down taking i_mutex and
the calling of filemap_write_and_wait() down into the ->fsync() handlers.  Some
file systems can drop taking the i_mutex altogether it seems, like ext3 and
ocfs2.  For correctness sake I just pushed everything down in all cases to make
sure that we keep the current behavior the same for everybody, and then each
individual fs maintainer can make up their mind about what to do from there.
Thanks,

Acked-by: Jan Kara <jack@suse.cz>
Signed-off-by: Josef Bacik <josef@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

2 files changed, 12 insertions, 11 deletions

diff --git a/fs/ubifs/file.c b/fs/ubifs/file.c
index 5e7fccfc4b29..89ef9a2f7837 100644
--- a/fs/ubifs/file.c
+++ b/fs/ubifs/file.c
@@ -1304,7 +1304,7 @@ static void *ubifs_follow_link(struct dentry *dentry, struct nameidata *nd)
         return NULL;
 }
 
-int ubifs_fsync(struct file *file, int datasync)
+int ubifs_fsync(struct file *file, loff_t start, loff_t end, int datasync)
 {
         struct inode *inode = file->f_mapping->host;
         struct ubifs_info *c = inode->i_sb->s_fs_info;
@@ -1319,14 +1319,16 @@ int ubifs_fsync(struct file *file, int datasync)
                  */
                 return 0;
 
-        /*
-         * VFS has already synchronized dirty pages for this inode. Synchronize
-         * the inode unless this is a 'datasync()' call.
-         */
+        err = filemap_write_and_wait_range(inode->i_mapping, start, end);
+        if (err)
+                return err;
+        mutex_lock(&inode->i_mutex);
+
+        /* Synchronize the inode unless this is a 'datasync()' call. */
         if (!datasync || (inode->i_state & I_DIRTY_DATASYNC)) {
                 err = inode->i_sb->s_op->write_inode(inode, NULL);
                 if (err)
-                        return err;
+                        goto out;
         }
 
         /*
@@ -1334,10 +1336,9 @@ int ubifs_fsync(struct file *file, int datasync)
          * them.
          */
         err = ubifs_sync_wbufs_by_inode(c, inode);
-        if (err)
-                return err;
-
-        return 0;
+out:
+        mutex_unlock(&inode->i_mutex);
+        return err;
 }
 
 /**
diff --git a/fs/ubifs/ubifs.h b/fs/ubifs/ubifs.h
index f79983d6f860..4cd648501fa4 100644
--- a/fs/ubifs/ubifs.h
+++ b/fs/ubifs/ubifs.h
@@ -1720,7 +1720,7 @@ const struct ubifs_lprops *ubifs_fast_find_frdi_idx(struct ubifs_info *c);
 int ubifs_calc_dark(const struct ubifs_info *c, int spc);
 
 /* file.c */
-int ubifs_fsync(struct file *file, int datasync);
+int ubifs_fsync(struct file *file, loff_t start, loff_t end, int datasync);
 int ubifs_setattr(struct dentry *dentry, struct iattr *attr);
 
 /* dir.c */